hey 55 1st burb i dont have an answer to the proper length of the frame for ya but some worthless insight i do have. when i was in highschool i worked at a truck shop on weekends and during the summer. i saw and actually modified many rear frame sections for differnet dump type hoists bodies. not sure if that is what happened to yours but thought i would pass that on. my $.02 thats really not even worth that for you right now
~army truck
